This study is an extension of a current prospective study of cardiovascular development from birth to age two through the ages three to five. The project will assess at what age in different ethnic, socioeconomic and sex groups: 1) tracking of blood pressure and of heart rate persists; 2) weight and weight change begin to be associated with blood pressure level; and 3) whether the level and the distribution of blood pressure among families of infants with consistently elevated blood pressure will differ from those among families of infants with consistently low levels of blood pressure. One hundred seventy white children and 115 black children will be examined in the home at ages three, four and five years. Blood pressure, heart rate, weight, height, and rectal temperature will be measured. Blood pressure, heart rate, weight and height will be measured on all siblings and parents. Three white families will be selected whose infants have consistently elevated blood pressure, and three white families whose infants have consistently low blood pressure. Blood pressure, heart rate, weight and height will be measured on all members of these six families and repeated one year later.